|School Name|City|Grades|Establishment|Charter|
|---|---|---|---|---|
|Aliamanu Intermediate School|Honolulu|7-8|1958||
|Anuenue School|Honolulu|K-12|1958|Charter|
|Central Middle School|Honolulu|6-8|1926||
|Dole Middle School|Honolulu|6-8|1955||
|Halau Ku Mana NCPCS|Honolulu|6-12|2000|charter|
|Jarrett Middle School|Honolulu|6-8|1955||
|Kaimuki Middle School|Honolulu|6-8|1939||
|Kalakaua Middle School|Honolulu|6-8|1928||
|Kawananakoa Middle School|Honolulu|6-8|1927||
|Moanalua Middle School|Honolulu|7-8|1967||
|Niu Valley Middle School|Honolulu|6-8|1955||
|Stevenson Middle School|Honolulu|6-8|1937||
|Washington Middle School|Honolulu|6-8|1854||

Question: how many schools were established before 1955?
Answer: 6